In the urinary organs, the influence of the menstrual period is manifested by a change in the urine. According to _Schrader_, the elimination of urea is diminished shortly before menstruation; according to _Laval_, the elimination of uric acid undergoes a sudden diminution on the second day of the flow, followed by an increase on the third day, subsequently rising above the normal level. This change is to be attributed, not to any excitation of the genital organs, but to the loss of blood. _Hebra_ already drew attention to the connection between diseases of the skin and the physiological and pathological processes occurring in the female genital organs; and emphasized the fact that for the cure of certain eruptions, local treatment of the disorder of the reproductive organs was requisite. He gave four examples of such eruptions: 1, an acute attack of eczema, which disappeared only after the removal of a badly fitting pessary; 2, in a chlorotic girl, two large red spots on the cheeks disappeared when menstruation was established; 3, improvement of a skin-affection when a coexisting disorder of the genital organs received appropriate treatment, followed by recrudescence of the skin trouble when the genital disorder became more severe; 4, a case of obstinate seborrhœa, lasting for many years, which disappeared only when the patient became pregnant, for the first time, seven years after her marriage. Similar cases have been recorded by subsequent observers, and numerous monographs have been published on menstrual skin-eruptions. _Schramm_, for instance, reports the case of a woman in whom at each menstrual period tubercles and papules appeared on the backs of the hands and on the neck; and the same author mentions another case in which during menstruation red papules arranged in rows appeared on the back. _Wilhelm_ observed dark blue macules, the size of hazelnuts, which appeared on the thighs shortly before menstruation and disappeared when the flow was over. Of two cases of menstrual disorder of the skin reported by _Stiller_, in one, an itching eruption appeared on the upper and the lower extremities; in the other, small red papules appeared on the dorsum of the hands and feet. Other cases of menstrual skin-eruptions were published by _Joseph_, _Pauli_, _Janovsky_, and _Schwing_. Sometimes at the menstrual periods severe pruritus vulvæ occurs, due, no doubt, to the temporary increase in the secretion of the menstrual passages, and to the more active influence exercised by this secretion on the vulva.